Experimental Study On Mechanical Properties Of UHPC-SMA Synchronous Gravel Layer

In order to comprehensively solve the two major problems of fatigue cracking and early damage of steel bridge deck pavement,the research team proposed an ultra-high-performance lightweight composite bridge deck system.Since the asphalt layer and the underlying UHPC in this system are rigid-flexible composite structures,the strong adhesion between the upper and lower structural layers(rigid-flexible interface)is a problem that needs to be paid attention to.In this paper,through indoor experimental research and numerical simulation analysis,the factors affecting the mechanical properties of the lightweight composite bridge deck system UHPC-SMA synchronous crushed stone adhesive layer are studied:(1)Analyze the types and performance characteristics of the bridge deck bonding materials,the performance requirements of the synchronous crushed stone of the adhesive layer,the testing methods of the mechanical strength between the layers at home and abroad,and the differences between the different methods.The types of materials for the waterproof adhesive layer of the bridge deck and the testing methods of the mechanical strength between layers are summarized and divided.At the same time,for the light composite bridge deck system,the type of bonding layer material suitable for bridge deck paving is recommended.(2)Through the experimental design,different types of asphalt,asphalt dosage,and crushed stone distribution amount are selected to simulate the synchronous crushed stone adhesive layer structure,and the oblique shear test is carried out at different test temperatures.The test results show that the order of the interlayer shear strength of the bonding material is high elasticity and high viscosity PG100>high elasticity and high viscosity(Bao Li)>SBS modified asphalt;There is an optimal amount of asphalt and gravel spread between UHPC-asphalt surface layer,1.4 kg/m~2 and 8 kg/m~2 respectively.(3)Through analysis of variance and grey correlation analysis,the influence of four factors,asphalt type,asphalt dosage,test temperature,and rubble spreading amount on the shear strength of UHPC-SMA adhesive layer is analyzed.From the results of the analysis of variance,it can be concluded that the four factors of asphalt type,asphalt dosage,test temperature,and rubble spreading amount all have significant effects on the shear strength of the UHPC-asphalt surface layer adhesive layer,and there are complex factors between different influencing factors Interactive influence.Among them,the asphalt type and the test temperature have a significant interaction effect on the shear strength of the adhesive layer.The calculation result of gray comprehensive correlation degree shows that:each influencing factor has a high correlation with shear strength,and 60℃dynamic viscosity,test temperature,asphalt dosage,penetration,ductility,softening point,and the amount of crushed stone have a high correlation with the viscosity.The degree of influence of layer shear strength decreases in order.Compared with penetration,softening point and ductility,the dynamic viscosity of asphalt at 60°C has a greater impact on the shear strength of the adhesive layer.When selecting adhesive layer asphalt materials,it should be used as a key index for evaluating modified asphalt binders.(4)Combining the finite element calculation results of the Queshi Bridge model and the calculation results of the allowable strength of the bonding layer,under the most unfavorable load combination,the engineering feasibility analysis of the synchronous gravel bonding layer can be obtained;whether it is normal temperature(25℃)or high temperature(60℃)),the high elasticity and high viscosity PG100synchronous gravel adhesive layer can meet the requirements of interlayer stress,and has sufficient safety reserves.